From your requirements to treat 52 as .52 you may need to divide by 100.0.

The nice thing about this approach is that it will respect the current locale. So, where appropriate it will format your example as "5.212,42".

Update:
I was, perhaps, a little speedy in posting my example. As pointed out by Conrad Shultz below, when dealing with currency amounts, it would be preferable to store the quantities as NSDecimalNumbers. This will greatly reduce headaches with rounding errors. If you do this the above code snippet becomes (assuming currency is a NSDecimalNumber*):